Thermostat



Dc. 31,'A 1929. l cfvoLKMAN THERMOSTAT Original 'Filed June 9. 1926 l au Patented Dec. 31, 1929 NuNrre-n :STATES PATENT OFFICE FREDERICK c. vom'lwmv, Vor" BALTIMORE, MARYLAND, AssIGNoR oF ONETHIRD To KENNETH H. AND SIDNEY c. VTNCENT, BOTH 0E BALTMORE, MARYLAND THERMOSTAT Appncation filed June e, 1926, seriai No. 114,758. Renewed 'May 2o, 1929.

This invention relates to improvements in thermost'ats, and more particularly to such devices for regulating Athe temperature in ovens of gas stoves, although it maybe advantageously used in other connections where it is desired to maintain a predeter-l mined temperature, as for instance, in hot water heaters and the Alike;l y

The thermostat belongs' to that class in which thermal o r thermostatic elements are employed which have different coeiiicien'ts of lineal expansion, whereby the 'valve is opened or closed more or less according to requirements, to admit or cut oli' the main supply of gas through the valve. K

I prefer that both thetheiinal elements be of metal, as for instance, a tube of aluminum, and a rod `of steel, 'forfvvith such material said elements are capa-ble 'of exerting both a pulling and pushing action not p`rac tical where one element 'is "of non-metallic composition, and the other element `of metal.A

Then too where both elements are metal, there is less likelihood 'of breal'zage, and the use of a spring or springs to 'seat the valve is avoided. V

There are other advantages flowing from the use of metallic lelements arranged and operated in the manner about to be described, that will become apparent to those skilled in these matters. l V

An important object of the invention is to so mount the valve upon the valve=ca`rrying Velement that within the range of comparatively high temperatures the relation between the valve and valve-carrying element will be substantially rigid or fixed, whereas in going from a high temperature to a low Vtemperature necessitating a movement of said element greater than the then existing valve port opening, and consequently suficient to `seat the valve, there will nevertheless still be permitted a frth'er contracting movement of 'saidA element:

This I accomplishby slidabl'y mounting the valve upon the element, and providing a compensatng Washer adapted whenthe exigencies for moving the valve slightly froiaits seat on the element have passed, to

yseat the valve in its normal position on said element. This washer which I ,preferably form 'of phosphor-bronze so that it will not lose its resiliency under high temperatures, is designed to perform a function other than that of keeping the valve seated on the ther# mal element, in that it bears against the face of the valve in such a way as to assist in making a gas-tight joint between the valve and the thermostat element upon which it is mounted, thus precluding the possibility `of leakage between the inlet and outlet portions of the valve body.

A still further advantage 'of this washer as I construct it, is that it is so formed that it may be readily removed, when the valve may be easily removed from the ther-mal element for cleaning the valve 'or the valve seat, after the cap covering one end of the valve body has been removed.

A further obj ect is to provide a simple and efficient means for establishing `a sliding con'- nection between the shaft 0f the settingwheel and the adjustable thermal element, whereby said element is permitted to freely expand and contract in accordance with the necessities incident to operation of the valve.

Another object is to provide a simple and eflicient means for maintaining a gas-tight joint between the setting-wheel shaft and the valve body or casing, which means, it will be noted, in the present instance, also performs the `function of maintaining the shaft in gas-tight position in the valve body. A device of this character becomes` intensely hot throughout, and therefore a further object of this invention is t-o provide the metallic and heat conducting parts, with a setting-wheel of a material of very low heat-conducting properties, so that regardless of the heat of the meta-l parts, the wheel will remain at a temperature entirely comfortable to the handof the operator in adjusting the thermostat for different temperatures.

In the drawings illustrating the invention:

Fig. l is a central sectional view of the thermostat, the valve being shown slightly off its seat. p ,Y y

Fig. 2 is a view of a certain portion of the central part of the valve bodyand contained parte, showing the valve seated on its periphwheel shaft.

eral seat, but slightly moved from its seat on the thermal element.

Fig. 3 is a perspective view of the settingwheel looking toward the inner side thereof and showing the graduations and markings by which the valve is adjusted for different temperatures.

Fig. 4 is a plan view of one of the spring washers. Y

Fig. 5 is an enlarged view of means for holding the setting-wheel in adjusted position.

Referring to the drawings, the numeral 1 designates the valve body or casing. This is hollow as usual, and is provided with an extension 2 internally threaded for the reception of the threaded end of a pipe or nipple leading from the gas supply, and this extension is therefore the inlet opening. At the opposite side 4of the casing is a similar extension 3 internally threaded for connection with a suitable outlet pipe. At the rear of the body is a boss 4, threaded as indicated at 5, for the reception of the threaded end of the tubular outer thermostatic member 6, which member is internally threaded at its other end as indicated at 7, for the reception of a. hollow screw plug 8, the plug being in` ternally threaded as at 9 for the reception of the threaded head 10 of the inner thermostatie member or rod 11. There is an opening 12 in the boss 4 for the passage of the enlarged part 13 of the thermal element or rod 11. The forward end of this rod is reduced as at 14, thus presenting a shoulder 15 against which normally abuts a boss 16 of the valve 17,

whose inner peripheral edge is refined for contact with the valve seat 18. Near the end of this rod is provided an annular groove 18 in which is seated a spring washer 18 with its outer peripheral edge bearing forcefully against the valve and holding it firmly in its seat on the rod 11 under proper conditions.

The rod is extended beyond the valve and is provided with a flattened end 19 adapted to be received in a kerf 20 in the head of the setting-wheel shaft 21. This shaft, as just intimated, is provided with a head 22 which fits and is held snugly against the face of the hub or boss 23 of the screw cap 24, which cap is flanged as indicated at 25, and is threaded into the valve body proper, and is therefore readily removable from the body. This setting shaft is provided outside the hub, with a narrow annular groove 26 for the reception of a concavo-convexed spring washer 27 which, when positioned in the groove, presents its peripheral edge forcefully against the hub, exerting a constant tendency to retract the To the end of the shaft is secured the setting-wheel 28, in which there is a central bushing 29 into which the end of the shaft extends and wherein it is held by a set-screw 30, which extends through a bore 31,

the end of the screw being threaded through the bushing and adapted to contact with the shaft, as is usual in such contrivances.

The setting-wheel has secured to its inner face, by cement or otherwise, a disc 31', formed with an annular integral flange 32, on the periphery of which are provided suitable degree markings or graduations, adapted, as usual, to be brought in line with a pointer 33 on the valve body.

The disc 31 is provided with a number of perforations 34 circularly arranged therein. These perforations are adapted to be entered by the head 35 of a spring-backed bolt 36 which works in a sleeve 37 secured to the screw cap 24. The bolt is recessed as indicated at 37', and a pin 38 enters the recess to permit the movement of the bolt, and to prevent the parts of this device from separating when the setting-wheel is removed. Then the setting-wheel is turned to adjust the thermostat the head 35 of the bolt will enter one or the other of the perforations 34 and will hold the wheel and consequently the thermostat members in adjusted position.

There is provided the usual by-pass 39 controlled by needle valve 39. This by-pass at all times, that is to say, at all times when the gas is turned on, permits a sufficient amount of gas to pass through the valve to maintain a small or pilot flame.

The setting-wheel is made of cork, either in one piece, or preferably of granulated or ground cork with the addition of a suitable adhesive. The wheel is then shaped and shellaced. It has been found by experiment that a wheel of this character, notwithstand ing the high temperature of the metallic parts with which it is closely associated, re` mains comfortable to the hand of the operator.

As intimated in the preamble, within the range of high temperatures, the valve remains seated upon the rod 11 and the range of adjustments will open the valve more or less as high or extremely high temperatures are required, but under some adjustment or adjustments in the low temperature range the valve would be entirely seated, due to the expansion of the thermal elements, drawing the part 14 through the valve and moving the shoulder 15 from the end of the boss 16, as shown in Fig. 2, and this movement is against the iniiuence of the spring compensating washer' 18, which will, under some operative conditions, immediately return the valve to its seat on the rod.

The outer thermal element 6, has a greater coefficient of lineal expansion than the inner element or rod 11, so that at elevated temperatures the valve 17 would be nearer to the seat- 18 were it not for the fact that the pitch of the threads on head 10 is greater than the resultant differences in length of the thermal elements 6 and 11, to a sufficient extent to almangos low the necessary gas to flow through the opening in the valve seat, to maintain the desired temperature. The construction is such ture changes in the oven to be effected in the minimum amount of time. The final opening between the valve and valve seat is always the diierence between the movement imparted by the pitch of the threads on head 10, and the resultant effect between the thermal elements 6 and 11. It is evident that the initial manual movement of the valve 17 must be greater than the eect of the ensuing temperature on the thermal elements. It is desirable to mount, as I have shown, the valve 17, on the inner thermal element 11, and in going from a higher temperature to a lower temperature, this xed relation between the valve directly abutted against the shoulder 15 of the element 11 is advantageous. However, in going from a lower temperature to a higher temperature which entails a move- Mment of the inner thermal element which is greater than the then existing port opening between the valve and the valve seat, it is important to provide means for allowing the inner thermal element to continue its travel Vinto the plug 8 after the valve 17 has seated itself on its seat. This means, I provide by so mounting the valve upon the rod that there is possible a longitudinal relative movement between the valve and rod, which movement `exerts an increased pressure on the compensating washer 18, whose normal tendency obviously is to keep the valve against the shoulder.

As hereinbefore stated, both the spring `washers 18 and 27 perform dual functions in that the influence of one holds the valve 17 seated against the shoulder on the thermal element and returns it to its seat under some conditions, and the washer 27 keeps the head "22 of the setting-wheel shaft in proper posirod. Toiaord quick removal of the wash ers, If prefer the form of washers shown in Fig-.4 wherein there is provided a large circular opening a of sufficient diameter to'permit it being passed over the rod 11 or the shaft 21, as the case may be, the opening verging into a smaller' opening .7) which is` located centrally of the washers,and is adapted to fit` snugly the diameter ofthe rod`11 or shaft 21,1asthe case may be, at the bottom: of( the grooves that are provided on these elements. The proportions of the openings inf the washer illustrated adapts it for use on the thermal rod 11, but obviously the washer whichis used in connection with the shaft` 21 willA have a larger offset opening sufficient for thepassage of the full diameter ofthe shaft, anda smaller centralopening to lit the diameter ofk theshaft from the'bottonrofl the` grooves;

In seating the valve in the first instance, it is placed in' an oven having' a glass door.'V Av thermometer is placed in the oven so that itv can be read from the outside; The valvesettingewheel is turned, say to SOOldlegrees, and the oven is allowed to heatfor" about 15l minutes. If the thermometer in the oven shows 350 degrees, the set screw inthe valve wheel-'is loosened and the wheelturneduntil` the pointer shows- 350k degrees.. Tlie theri mostat is? then' readyfor use;V Say" for' in'-` stance, it is desired to set' itl for a temper;` ature of 350 degrees, the setting-wheel is turiietlto 550degrees; Tlii's will unscrew therod 11` and open-l the valve to a small' extent, the' gas flame-burning high.v 'Ilhe expansion of the2 thermal elements as beforestated, (of steel andV aluminum)` will close the valve sufficiently to allow enough gas to pass throughto maintain 550 deg`rees y Now the valve wheelis turned back to'250 degrees@ The opening between the valve andj tlieifalve seat at' 550 degrees' is' about .013.` In turning the valve wheel from `55O`tor250-`I you screw in-` steel rod-` about half turn which is about .023. Consequently thevalve ifs1 seated and? compensation washer is com- Y pressed (the valve' being movable on rodi) .023- .013 or .010. The two elements, tube and rod are now cooling, which graduL ally relieves compression of washer and opens valve to about .0017 which allows enough gas to pass through valve to'maintain 250`degrees.

If the compensating washe`r`18"l were not used, the valve" would closetiglit, and it would be impossible to turn the valve wheel toV 250l iccs iraidegrees unless suliicient time were" allowed to A elapse until the thermal element 11V cooledi down or contracted` sufficiently toallow enough gas to pass through the'va-l-ve to main o.

tain `.250 degrees.

The construction whereby the valve may be readily reached for cleaning purposes has been described, and I may a'dd, that not only is the interior of' the thermostat readily `aclcured to said shaft, aithermal element comprising a rod having a sliding connection with said shaft, whereby when said wheel is rotated the rod is moved longitudinally, a valve on said rod and capable of longitudinal movement thereon, means for holding said valve in a definite position on said rod, said means being also adapted to return said valve to such position after it has been moved therefrom.

y 2. In combination, a hollowT valve body having an inlet and an outlet, a valve seat between the two, thermostatic elements associated with said body, comprising a tube secured to said body and a rod within the tube land adjustably secured thereto, the rod and tube having different coeicients of expansion, a valve seat on the rod within the body, a valve mounted slidably on said seat, a spring washer secured to said rod and bearing against the valve to hold it normally seated, a screw cap closing one side of the body, a shaft within said cap, a setting-wheel adj ustably secured to the shaft outside the body, said shaft being providedwith a recess within the body adapted to receive the inner end of the rod whereby when the shaft is turned, the rod is rotated, the recess in said shaft being of sucient depth to permit the expansion of said rod.`

3. In combination, a hollow valve body having an inlet and an outlet, a valve seat between the inlet and outlet, a screw cap closinvr one side of the body and having journalled therein a shaft provided with a recessed head, a setting-wheel adj ustably secured to said shaft, resilient means interposed between the cap and the wheel tending to seat the head of the shaft against the cap, a thermostatic element comprising an adjustable rod having one end extending into the recess in said shaft, a valve on said rod and capable of longitudinal movement thereon, means for keeping said valve in a definite position on said rod, said means also serving to return said valve to such position after it has been moved therefrom.

4. In combination, a hollow valve body having an inlet and an outlet, a valve seat be tween the two, thermostatic elements having different coefficients of lineal expansion associated with said body, one element comprising a tube and having an internally threaded plugVr therein, and the other a rod provided With threads cooperating with the threads of the plug, the rod extending within the hollow body and there provided with a seat, a valve mounted on said seat and capable of longitudinal movement on the rod, a removable spring washer secured to the rod and bearing against the valve for the purposes set forth, a screw cap closing one side of the body and having journalled therein a shaft provided with a recessed head, the recess therein being' adapted to receive the end of said rod, and a setting-wheel adj ustably secured to the outer end of said shaft whereby when said shaft is rotated, the rod will be adjusted according to predetermined temperatures desired.

In testimony whereof I aiiiX mv signature.

FREDERICK C. VOIJKMAN. 

